Method of making rubber printing plates



sept. 21, 1943. F. Moss ETAL l2,330,002

METHOD OF MAKING RUBBER PRINTING PLATES Filed March '7, 1941 ,17 @Zig-.Z

18 J9 -9 J5 ZZ J9 (IZ 'ZZ @g5- 17 17 JZ 15 14 3,6 Z3 JZ Z6 .an Z9 J5 14Z k W www Patented Sept. 21, 1943 METHOD or MAKING RUBBER PRINTINGPLATES Franklin Moss, Hollis, and John F. Kirby, Jr.,

Brooklyn, N. Moss Y.; said Kirby assgnor to said Application March 7,1941, Serial No. 382,128

9 Claims. (Cl. 101-401.1)

vThis invention relates to a method for producing printing plates ofrubber or like material.

It is a general object of the invention to provide a method for makingrubber printing plates whereby the resultant product may be employed togive good printing results and whereby perfect printing register may beobtained among a plurality of such plates when used for multicolorprinting. Another object ofthe invention is to provide a method wherebya printing plate is produced which is non-shrinkable and non-`distortable so that true reproduction of the subject matter to beprinted, may be obtained.

Another object of the invention is to provide a method for producingrubber printing plates which are provided with means whereby exactpositioning of said plate upon a press may be obtained so that hair lineregister in multi-color printing may be obtained.

The invention also seeks to provide a novel form of printing plate oflaminated construction to obviate stretch and shrinkage, and which isprovided with means for obtaining accurate registry location of saidplate in a printing nate step Vin the method.

Fig. 8 is Va broken perspective view of a printing plate produced by themethod shown in Figs. 1-7.

Fig. 9 is a fragmentary detail sectional view illustrating an alternateform of means for mounting the printing plate upon a pressA cylinder.

In that form of the invention which is illustrated in Figs. 1 to 6, ametal photo-engraving isl produced in the usual way from a drawing orphotograph, and is represented at I0. These plates, usually of zinc, arepreferably provided with standard Vandercook or4 similar register marksas may be well understood. In the present instance, it is preferred todrill the holes I I at the center of these register marks.

The zinc plate thus provided is then placed upon a moulding plate suchas I2, and the holes I I employed to guide the forming of similarregistering holes I3 therein. The zinc plate I0 is then removed and thenew holes I3 are used to guide the drilling of holes Il. The latterholes are preferably drilled to obtain the conical end 'seats I5 and arepreferably located along a line drawn through the centers of the holesI3.

The zinc plate I0 is then replaced upon the moulding plate I2 andsecured thereto as by pins I6 in the -registered holes ll'and I3 and theassembly thus provided placed in a press and preferably secured to theram II thereof.

A second moulding plate I8 is provided for association with a mouldingplate I2, one of saidk moulding plates being provided with openings I9and the other with cooperating pins 20 so that telescopic engagementtherebetween may be had. The plate I8 is then mounted in the press andpreferably on the platen 2| thereof.

The two moulding plates and the zinc plate I0 are first employed forforming a matrix which represents the reverse of the material on thezinc plate. In the present instance, the matrix is preferably formed ofplastic material such as Bakelite and is accomplished in the followingmanner:

VA bonding sheet 22 is cemented to the moulding` plate I8 and thereupona matrix sheet 23, preferably of a phenolic resin compound, is placed.The press is then closed to cause the zinc plate I Il to impress itsimage in the matrix sheet. This is best seen in Fig. 2 wherein, inaddition to pressure, heat is also applied. The matrix 24, being nowformed, and the matrix sheet bonded tothe bonding sheet 22 by thementioned heat and pressure, the press isopened.

After the matrix 24 is formed, the upper mouldingv plate I2 is removedleaving the moulding plate I8 with the matrix thereon. A sheet of rubber25 is then placed over the matrix to cover the same and a fabric sheet26 superimposed on said rubber sheet as shown in Fig. 3'. Press pressureand heat are then applied to cause the rubber sheet to be forced intothe matrix to be formed into the printing sheet 2'I. This condition isshown in Fig. 4.

` The press parts are again separated, the moulding plate I2 replaced,and a second rubber sheet 28 placed upon the fabric sheet 26, as seen inFig. 5. The press is again closed and the second sheet 28 will becompressed to become bonded to the fabric sheet 26 and so that portionsof said sheet 28 will be forced into the holes I 4 in the moulding plateI2, to form projections 29 having conical ends 30 formed by the conicalend seats I5. Fig. 6 shows this condition.

The printing plate thus produced comprises the printing sheet or layer2l, a backing sheet or layer 23, and an intermediate fabric sheet 28,

. bonded to each other by the heat and pressure applied by the press.The fabric sheet 26 is provided to prevent undue shrinkage of the platethus formed during curing thereof and provides an article which may beeasily handled without danger of undue distortion. The projections 29'formed on the backing sheet 28 provide means for obtaining perfect hairline registration and location of the printing plate thus formed on anyroller or bed provided with holes for their reception. The conical ends30 allow for easier insertion of the projections into the holes in thepress. Should these provisions not be made in a press, then a jig inwhich such holes are formed, may be employed for mounting the printingplate on a press.

The moulding plates I2 and i8 may now be used for making other printingplates for registering colors of a multi-color printing job. Thus,starting with a new zinc plate I0, a matrix for the new color plate maybe formed, and then the color plate itself. Each new plate will beprovided with projections 29 and assurance is had that when mounted in aprinting press, the impressions or all of the plates will have perfectregister.

lt will be noted that the matrix 24 is bonded to the moulding plate I8.In order to facilitate ready removal thereof, and perhaps for futureuse, an adapter plate 3| may be interposed as shown in rig. 7. Thislatter plate may be removaniy mounted on the moulding plate I8 in amanner sinniar to the mounting of the zinc plate nu on the mouldingplate I2. now remain with the adapter plate when removed.

'lne invention may be practiced in other ways. bor instance, as shown inFig. 9, the rubber sheet zu, instead oi the projections 29, may beformed witn seats 32 by projections on the moulding plate i2. The keyingmeans for the cylinder or bed C may comprise metal pins 33 which may beremovably set in seats in the cylinder or bed and have projectingportions 2i!a for engagement in the seats 32. The pin seats 33 areprepared in the following manner.

A sheet 34 of double faced adhesive sheet is wrapped about the cylinderC or applied to the bed of the press. The adhesive sheet, at theselective seats, is punched through and the pins 33 inserted therein.The printing plate is then set upon the pin projections 29a by matchingthe seats 32 with said projections and pressing the plate down firmly toadhere it to the adhesive sheet 34. For greater accuracy and to preventundue spreading of the sheets 34, they may each be reinforced by afabricdisc or washer 35.

If desired, the metal pins 33 may be moulded with the rubber plate 28 sothat they are inseparable therefrom to insure against relative movementbetween said pins and the plate 28.

As can be well understood, the cylinder or bed may be formed with aplurality of pin seats 33 which may be selectively employed forpositioning either one printing plate or a number of smaller individualprinting plates. By the use of the adhesive sheet 34 and at least twopins for each printing plate, all of said plates may be mounted Thematrix may in the press with assurance that they will remain aspositioned.

From the foregoing it is readily apparent that a novel and eillcientmethod has been provided for producing a rubber printing plate of novelform. While the steps of the method illustrated are at presentpreferred, they may be varied within the principles of the inventionwithout departing from the general spirit and scope of the invention asdefined in the appended claims.

What we claim as new and desire to secure by Letters Patent, is:

l. The method for making a printing plate which consists in providing amoulding plate with a plurality of holes, some of which are registryholes, mounting a photo-engraving on said moulding plate by means ofpins in the registry holes, forming a matrix from said photo-engravingand adhering said matrix to a second moulding plate, forming a printingplate in said matrix and simultaneously bonding a non-shrink sheet tosaid printing sheet, and then bonding a backing sheet to said non-shrinksheet and simultaneously forming projections on said backing sheet byforcing portions thereof into the mentioned holes in the moulding plate.

2. The method of making a printing plate which consists in applying heatand pressure to a fabric-backed rubber sheet disposed between a mouldingplate provided with a matrix and a moulding plate formed with aplurality of holes to form a printing sheet having a bonded fabric back,separating the moulding plates, placing a second sheet of rubber on thefabric back, and 35 again applying heat and pressure to bond said secondsheet; to said fabric back and to force some of the material of saidsecond sheet into the holes in the mentioned moulding plate.

3. The method of making a printing plate 49 which consists in firstforming a printing sheet of rubber having a bonded fabric back, and thenbonding a rubber backing sheet to said fabric back and' simultaneouslyforming a plurality of projections on said latter sheet.

4. The method of making a printing plate which consists in providing afirst moulding plate with registry holes transferred from aphotoengraving and with a plurality of holes in register with saidregistry holes, mounting the men- 59 tioned photo-engraving on saidfirst moulding plate by means of pins in the registry holes, placing thephoto-engraving mounted moulding plate in a pressure machine, placing asecond moulding plate in said pressure machine in cooperative relationwith the first moulding plate, placing matrix material upon said secondmoulding plate and applying heat and pressure to cause a matix carriedby the second moulding plate to be formed, removing the first mouldingplate and 60 the photo-engraving from the pressure machine,

placing a sheet of rubber on the matrix, superimposing a fabric sheet'onsaid sheet of rubber and applying heat and pressure to impress the-mati'i'x on the sheet of rubber and to bond the fabric sheet thereto,replacing the rst moulding plate in the pressure machine, placing asecond sheet of rubber on the fabric sheet and applying heat andpressure to bond said second rubber sheet to the fabric sheet and toforce portions of said second rubber sheet into the holes in said rstmoulding plate.

5. In a method for making rubber printing plates, the steps oftransferring the registry marks of a photo-engraving to a mouldingplate,

and forming a plurality of projection-forming 9. 'I'he method of makinga printing plate holes in said moulding plate in registering relation tothe transferred marks, and of utilizing the said holes to form keyingprojections on the backs of the printing plates.

6. In a method'for making rubber printing plates, the steps of`transferring the registry marks of a photo-engraving to-a mouldingplate,

- forming a plurality of projection-forming holes in said moulding platein registering relation to the tranferred marks, mounting thephoto-engraving with its registry marks in register with the transferredmarks on the moulding plate, and forming a matrix of saidphoto-engraving.

'7. The method of' making a printing plate which consists in applyingheat and pressure to aV fabric-backed rubber sheet disposed between amoulding plate provided with amatrix vand a second moulding plate toform a printing sheet y 8. The method of making a .printing plate' whichconsists in first forming a printing sheet of rubber having a bondedfabric back, and then bonding a rubber vbacking sheet to said fabricback and simultaneously forming a pluralityof keying means on saidlatter sheet.

which consists in providing a first moulding plate with registry holestransferred from a photo-engraving, mounting the mentionedphoto-engraving on said first moulding plate by means of pins in theregistry holes, placing the photo-engraving mounted moulding plate in apressure machine, placing a second moulding plate in said pressuremachine in cooperative relation with the first moulding plate, placingmatrix material upon said'second moulding plate and applying heat andpressure tof cause a matrix carried by the second moulding plate to be'formed, removing the rst moulding plate and the photoengraving from thepressure machine, placinga sheet of rubberfon the matrix, superimposinga a second sheet of rubber on the fabric sheet andA applying heat andpressure to bond said secondl rubber sheet to the fabric sheet and toform keying seats in the second rubber sheet by the mentioned pins inthe last mentioned moulding plate.

'FRANKLIN MOSS.

JOHN F. KIRBY, JR.

